Activation of envelope stress response pathways during long chain fatty acid metabolism in Escherichia coli

Abstract

A bacterial cell envelope is a complex extracytoplasmic compartment, which serves as a protective layer separating cytoplasmic space from diverse external environment. Any perturbation in the components of this cell envelope triggers envelope stress responses (ESRs) which convert extracellular (physical or chemical) stimuli to specific cellular response through combination of various transcriptional regulatory networks. Here, we tried to explore whether metabolism of carbon sources affects the envelope of bacteria. In this direction, we investigated the induction of various ESR pathways in response to utilization of long chain fatty acids (LCFAs) as a carbon source by E. coli. We used reporter constructs where lacZ gene was fused with promoter of representative regulon members of ESR pathways and β-galactosidase assay was performed. We observed activation of major ESR pathways in the presence of LCFAs and their induction was dependent on LCFA utilization. Activation of ESR pathways in cells grown in LCFAs suggests envelope stress during LCFA metabolism. In our future work we will try to understand the reason for this stress in the envelope and the mechanism by which ESR pathways counteracts such stress.